The present inventive concepts described herein relate to power supplies of semiconductor memories and more particularly, to auxiliary power supply devices and nonvolatile memory systems including the same.
Semiconductor memory devices are memory devices implemented using a semiconductor such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), and indium phosphide (InP). In general, semiconductor memory devices are classified into volatile memory devices and nonvolatile memory devices.
Volatile memory devices lose their stored data when their power supplies are interrupted. Nonvolatile memory devices may include a static RAM (SRAM), a dynamic RAM (DRAM), and a synchronous DRAM (SDRAM). Nonvolatile memory devices are memory devices that retain their stored data even when their power supplies are interrupted. Nonvolatile memory devices may include a read only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory device, a phase change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (ReRAM), and a ferroelectric RAM (FRAM).
Since nonvolatile memory devices retain their stored data even when their power supplies are interrupted, nonvolatile memory devices may be used as a mass storage medium. In general, a nonvolatile memory system including nonvolatile memory devices and a memory controller controlling the nonvolatile memory devices operates with externally received power. Power may be suddenly shut off while the nonvolatile memory system operates, which is called sudden power-off. At this point, data stored in the nonvolatile memory device is not lost. However, since the memory controller may also store important data using a volatile memory such as SRAM or DRAM, data stored in the memory controller may be lost or may not complete an operation that the nonvolatile memory device is performing (e.g., an erase operation, a write operation, etc.).
In order to address the above disadvantages, the nonvolatile memory system can perform a sudden power-off operation using an auxiliary power supply to complete the operation that is being performed and to back up the important data immediately after the sudden power-off occurs, the peak power required to complete the operation that is being performed can increase. During the subsequent data backup operation, a long-term supply of power at a lower peak power may be required instead. The auxiliary power supply may include a plurality of capacitors or a high-capacity battery to meet both a requirement for high peak power immediately after the sudden power-off occurs as well as a requirement for a low peak current for a long time. However, the area occupied by such an auxiliary power supply may increase due to the capacitor or the high-capacity battery.